Study of Ag porous film using X-ray reflectivity and pattern formation using Atomic Force Microscope

Surface Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhan nagar, Calcutta 700064, India

Corresponding author: sangam@cmp.saha.ernet.in

Received: 18 May 2001
Revised: 3 August 2001
Accepted: 26 September 2001
Published online: 15 February 2002

Abstract

Ultra thin film of Ag deposited using magnetron sputtering were found to be porous in nature and its porosity reduces with the increase in thickness. We present here some results on formation of periodic pattern having nano-size wire like structure on this porous film of Ag deposited on Si(001) substrate using the tip of the Atomic Force Microscope (AFM) cantilever. This pattern is induced by the interplay of tip-surface interaction and the adhesive force between the Ag particle and the substrate. The periodicity and growth direction of the wire like structure is mostly determined by the thickness of the deposited film. With the increase in thickness of the Ag film the growth direction of these wires changes from 45° angle to 90° angle to the scan direction. We have also observed that if the thickness of the deposited film is below a critical thickness then a carpet like growth occurs and beyond this critical thickness the film undergoes mound formation. The mound size increases as the thickness of the film increases. The onset of the mound growth inhibits the formation of the pattern induced by the tip of the AFM cantilever. This process of the pattern formation of the ultrathin films may have a wide application in the field of nanotechnology.